Results of 6500 measurements show the average 2 2 2 Rn concentrations in premises of different regions of the Ukraine. The main rules of radon levels formation. The weighted dose of irradiation of the population due to 2 2 2 Rn in the air of residential premises stood at 4.2 mSv y - 1 and formed up to 79% of the total natural irradiation dose. Collective doses have been evaluated for most Ukrainian regions. Studies confirm the need for development of effective countermeasures aimed at reduction of radon levels in the air of premises that will lead to the decline of total irradiation doses and, as a result, radiation risks for the population of the Ukraine.